The present invention relates to a wiring board (printed circuit board) for press-connection of circuit boards, modules and connectors, and an electronic device having the circuit board.
In recent years, as a connection method upon mounting parts and the like on a circuit board where electric wires are formed, press-fit connection attracts attention. Conventionally, the press-fit connection is used in a main frame computer or the like as solderless connection method to remove difficulty in soldering between circuit board. However, in recent years, the press-fit connection is more frequently applied to an on-vehicle electronic device such as ABS (Antilocked Braking System) since (1) the connection process is simple, (2) the equipment investment to establish the process is small, and (3) it is possible to realize higher density mounting in comparison with soldering.
Japanese Patent Application Laid-Open Publication No. 2004-134302 discloses dispersing stress on a circuit board between through holes by changing a press-insertion direction of a press-fit terminal so as to improve the reliability of the circuit board. According to this method, when a part is arranged between the through holes, it is possible to reduce the stress applied on the part.
Japanese Patent Application Laid-Open Publication No. 2008-294299 discloses inserting a press-fit terminal in a printed circuit board having a metal core so as to improve the reliability. According to this method, as the hard metal core receives the distortion of the terminal, it is possible to reduce the distortion of the printed circuit board.
In the method disclosed in Japanese Patent Application Laid-Open Publication No. 2004-134302, high stress is applied in a direction where the distortion is initially small. Accordingly, regarding the direction in which the spring force acts, it is necessary to arrange the part away. This cases wasteful space. Further, high density mounting is limited.
In the method disclosed in Japanese Patent Application laid-Open Publication No. 2008-294299, the metal core board is not widely used since the cost of the metal core board is generally high.